1. Field of the Invention
The present invention relates to a car engine controller.
2. Description of the Prior Art
FIG. 14 is a block diagram of a car engine controller of the prior art disclosed by Japanese Laid-open Patent Application No. 6-2441105. In FIG. 14, reference numeral 101 denotes an acceleration opening sensor, 102 an air volume sensor, 103 an engine speed sensor, 104 a measuring unit, 105 a control unit, 106 an engine output control unit in the control unit 105, 107 a monitoring unit in the control unit 105, 108 a fuel control unit in the control unit 105, 109 output means, 110 a throttle actuator, 111 a fault indicator, 112 a fuel injector and "b" a connector.
A description is subsequently given of the operation of the above car engine controller. The accelerator opening sensor 101 detects the opening of an accelerator which is the operation amount of an accelerator stepped on by a driver, converts it into a signal and outputs the converted signal to the engine output control unit 106 and the monitoring unit 107. The measuring unit 104 outputs momenta such as an engine speed, engine temperature, car speed and gear ratio to the engine output control unit 106. The engine output control unit 106 computes a throttle drive signal from the opening of the accelerator input from the accelerator opening sensor 101 and the momenta input from the measuring unit 104 and control the throttle actuator 110 through the output means 109 based on the result of computation. The throttle actuator 110 adjusts the opening of the throttle valve of an engine to control the output of the engine. The air volume sensor 102 detects the amount of intake air to be absorbed to the engine side from the throttle valve, converts it into a signal and outputs the converted signal to the fuel control unit 108. The engine speed sensor 103 detects an engine speed, converts it into a signal and outputs the converted signal to the fuel control unit 108. The fuel control unit 108 computes the amount of fuel injection from the amount of intake air input from the air volume sensor 102, the engine speed input from the engine speed sensor 103 and the momenta input from the measuring unit 104 and controls the fuel injector 112 based on the result of computation. The fuel injector 112 injects fuel. The engine is thereby supplied with fuel and air required for combustion to be driven.
The monitoring unit 107 sets a maximum value for a signal indicative of a load on an operation area such as the accelerator operated by the driver according to the opening of the accelerator input from the accelerator opening sensor 101 and compares the maximum value with a load value such as the basic amount of fuel injection from the fuel control unit 108. When the load value is larger than the maximum value, the monitoring unit 107 judges that a failure occurs and outputs the result of this judgment to the engine output control unit 106, the fuel injection control unit 108, the output means 109 and the fault indicator 111. Thereby, a failure reaction or emergency driving reaction is carried out.
Since the car engine controller of the prior art is constituted as described above, the maximum value of load must be set and there is a possibility that the undesired processing of a failure is carried out according to the setting of the maximum value. The amount of load on the engine is affected by various changing factors such as the temperature and operation states of the engine and exact judgment on a failure may not be made.
It is therefore an object of the present invention to provide a car engine controller which can avoid the undesired processing of a failure by processing without making the driver know the failure even when an abnormal value is computed.